LED desktop lamp. You can turn it into a light source for studying or a monitor light.

Penholder. Keep track of all of your pens on your desktop!

Cell phone stand and charger. It can hold your mobile device and charge it via USB at the same time as soon as you connect the cable.

Hidden flash drive. You can have an undetectable flash drive that the computer cannot see, unless you trigger the LDR sensor by a single LED flashlight. The flashlight generates a small signal on the LDR surface and that small signal is enough to BASE Biasing of the transistor to allow a significant current through the relay coil and turn on the positive DC source for the flash drive.

Samimy break's down the project into a few steps below, also providing a PDF file of the schematics if you're skilled enough to follow his footsteps.